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I had a very educational exchange the other day on Twitter (also known as “getting schooled”) by my SQL compatriots Argenis Fernandez (@DBArgenis) and Hugo Kornelis (@Hugo_Kornelis). A guy called Chris Switalski (@crswit) asked a really interesting question on #sqlhelp, which I proceeded to answer incorrectly, which led to a correction by my ...

Version 1.0 is Now Available! Edit 9 October 2013: A new version is out! Please download 1.2 from here.
I’ve been working off and on, as my real job permits, on this visualization tool for SQL Server data files. This is an educational or exploratory tool where you can more readily see how the individual data pages in MDF/NDF files are ...

This is part three of a blog series illustrating a method to render the file structure of a SQL Server database into a graphic visualization.
Previous Installments:
Part 1
Part 2
Those that have been reading this series might be be thinking, “Is he going to go there?” Well, the answer is “Yes.” This is the GUID clustered index post that had to ...

Part 2 of a blog series visually demonstrating the layout of objects on data pages in SQL Server
Part 1
In Part 1 of this series, I introduced a little demo app that renders the layout of pages in SQL Server files by object. Today I’ll put that app through its paces to show, in vivid color (well, teal, anyway) the destructive power of the famous ...

Part 1 of a blog series visually demonstrating the layout of objects on data pages in SQL Server
Some years ago a gentleman called Danny Gould created a free tool called Internals Viewer for SQL Server. I’m a visual sort of guy, and I always thought it would be fun and educational to make a simple visualizer, like the one he created, in order to ...

I thought I had said almost all that could be said about nonclustered index keys in a post made almost exactly two years ago, on March 16, 2008. But there's more.
To get all the benefit from today's post, you'll really have to read that one, but I'll synthesize the crucial details here.
Every index needs to be unique, in some way or ...

I recently received a question about the storage of nonclustered index keys. I am assuming you are aware of the fact that if your table has a clustered index, SQL Server uses the clustered index key (all of its columns, if it is a composite index) as a 'bookmark' in your nonclustered indexes, to allow your nonclustered indexes to uniquely ...

Yet another fragmentation post, to answer a question asked in response to a previous answer....
SQL_Girl is still confused about DETAILED vs LIMITED, and I don't blame her. She reported that the BOL says: ''The nonleaf levels of indexes are only processed when mode = DETAILED. '' But I had said: ''The second misunderstanding involves ...